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A109118 a(n) = 2*(n^2 + 3*n + 1)^3. 1
2, 250, 2662, 13718, 48778, 137842, 332750, 715822, 1409938, 2590058, 4496182, 7447750, 11859482, 18258658, 27303838, 39805022, 56745250, 79303642, 108879878, 147120118, 195944362, 257575250, 334568302, 429843598, 546718898 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Kekulé numbers for certain benzenoids.

REFERENCES

S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 310).

LINKS

Table of n, a(n) for n=0..24.

FORMULA

G.f.: 2*(1 + 118*z + 477*z^2 + 132*z^3 - 13*z^4 + 6*z^5 - z^6)/(1-z)^7.

MAPLE

A109118:=n->2*(n^2+3*n+1)^3: seq(A019118(n), n=0..30);

MATHEMATICA

Table[2 (n^2 + 3 n + 1)^3, {n, 0, 30}] (* Wesley Ivan Hurt, Feb 04 2017 *)

CROSSREFS

Cf. A028387.

Sequence in context: A024349 A012529 A012527 * A034313 A177320 A304211

Adjacent sequences:  A109115 A109116 A109117 * A109119 A109120 A109121

KEYWORD

nonn,easy

AUTHOR

Emeric Deutsch, Jun 19 2005

STATUS

approved

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Last modified July 11 23:47 EDT 2020. Contains 335653 sequences. (Running on oeis4.)